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Table 1 Confounding variables adjusted for in the model.

From: Solar ultraviolet-B exposure and cancer incidence and mortality in the United States, 1993–2002

Variable Definition Source Geographic Level Sex-specific Race-specific
Age 10-year age groups from 35–44 to 75–84, and 85+ SEER County X X
Poverty % of households below poverty rate 2000 US Census County X X
Income Median household income in dollars 2000 US Census County   X
Smoking Age-adjusted lung and bronchus cancer mortality rate SEER County X X
Exercise % with no exercise in last 30 days BRFSS 1994–2002 (even years) & 2001 State X X
Alcohol Average number of drinks in past 30 days BRFSS 1997, 1999, 2001, 2002 State X X
Outdoor occupation % of workers in agriculture, forestry, fishing, hunting, or construction 2000 US Census County X  
Urban/rural % rural population Average annual PM2.5 concentrationa 2000 US Census County   
Air quality (values for ~ 600 counties known, remainder were interpolated) US EPA AirNow database 2000 County   
  1. a Particulate matter results in an overestimation of surface-level ultraviolet exposure indicated by the TOMS data, since particulate matter absorbs ultraviolet radiation [46]